Dose-reduced [18F]PSMA-1007 PET is feasible for functional imaging of the renal cortex

Abstract

Background In Prostate-specific membrane antigen (PSMA) positron emission tomography with computed tomography (PET-CT), there is significant renal uptake. The standard in renal cortical functional imaging is scintigraphy with technetium-99m labeled dimercaptosuccinic acid (DMSA). Using [68Ga]Ga-PSMA-11 PET for renal imaging has been suggested, but using [18F]PSMA-1007 has not been explored. The aims of this study were to establish the optimal time point for renal imaging after [18F]PSMA-1007 injection, to investigate the reproducibility of split renal uptake measurements, and to determine the margin for reduction in administered activity. Methods Twelve adult male patients with prostate cancer underwent [18F]PSMA-1007 PET-CT at 8 time points up to 5.5 h post-injection (p.i.). List-mode data were binned to durations of 10 to 120 s per bed position (bp). Left renal percentage of total renal uptake (LRU%) was measured, and the difference between highest and lowest measurement per patient (“delta max”) was calculated. Images acquired at 1 h, 2 h, and 5.5 h p.i. with durations of 10 to 120 s/bp were rated regarding image quality. Results Imaging at 2 h p.i. with 60 s/bp yielded acceptable quality in all cases. Increasing acquisition time to 15 min for a single bp would allow reducing administered activity to 0.27 MBq/kg, resulting in an effective dose of 0.4 mSv for a 1-year old child weighing 10 kg. The median delta max of LRU% measurements was 2.7% (range 1.8–7.3%). Conclusions Renal [18F]PSMA-1007 PET-CT is feasible, with imaging 2 h p.i., acceptable split renal uptake variability, and effective dose and acquisition time comparable to those of [99mTc]Tc-DMSA scintigraphy.

[18F]-PSMA-1007-PET for evaluation of kidney function

“…In contrast, the potential strength of PSMA-PET for renal imaging lies in its good availability and the possibility to infer meaningful information on kidney function from PET originally performed for prostate cancer imaging [19]. A recent study demonstrated the feasibility of [ 18 F]-PSMA-1007 PET to substitute renocortical [ 99 m Tc]-DMSA-scintigraphy which renal PSMA radiotracer uptake probably most closely corresponds to [10]. In contrast to [ 99 m Tc]-DMSA, [ 99 m Tc]-MAG3-scintigraphy plays an important clinical role in adult patients and provides in addition to split renal function valuable information on absolute function (TER-MAG3) and possible obstruction, which is particularly relevant in prostate cancer patients.…”

“…In contrast, the 18 F-labelled radiotracer [ 18 F]-PSMA-1007 is not excreted by the kidneys and therefore the renal signal should dominantly derive from tracer bound in the renal cortex. In a recent study, the utility of [ 18 F]-PSMA-1007 to substitute for renal scintigraphy was evaluated based on measurements of different time points and simulated dose reductions in a cohort of 12 patients with predominantly healthy kidneys [10].…”

[18F]PSMA‐1007 renal uptake parameters: Reproducibility and relationship to estimated glomerular filtration rate

“…Despite its name, PSMA is also expressed in non‐prostatic tissues, such as the proximal tubules of the kidneys (Kinoshita et al, 2006 ; Silver et al, 1997 ). Two PSMA radiopharmaceuticals for PET use, 68 Ga‐PSMA‐11 and 18 F‐PSMA‐1007, display significant renal uptake and are being explored as alternatives to 99m Tc‐DMSA scintigraphy for renal cortical imaging (Ahmadi Bidakhvidi et al, 2021 ; Sarikaya et al, 2018 , 2021 ; Valind et al, 2021 ).…”

[18F]-PSMA-1007-PET for evaluation of kidney function

“…A recent study demonstrated the feasibility of [ 18 F]-PSMA-1007 PET to substitute renocortical [ 99m Tc]-DMSA-scintigraphy which renal PSMA radiotracer uptake probably most closely corresponds to [10] ROC analyses to determine any sign ciantly abnormal uptake (Unilateral SRF MAG3 <40%) (A ,B) and analysis for highly abnormal uptake (Unilateral SRF MAG3 <25%) (C, D). .…”

“…In contrast, the 18 F-labelled radiotracer [ 18 F]-PSMA-1007 is not excreted by the kidneys and therefore the renal signal should dominantly derive from tracer bound in the renal cortex. In a recent study, the utility of [ 18 F]-PSMA-1007 to substitute for renal scintigraphy was evaluated based on measurements of different time points and simulated dose reductions in a cohort of 12 patients with predominantly healthy kidneys [10].…”